1. Field of the Invention
Exemplary aspects of the present invention generally relate to a sheet feeder and an image forming apparatus including the sheet feeder.
2. Description of the Related Art
One type of image forming apparatus such as a printer, copier, plotter, facsimile machine, or multifunction device having two or more of these capabilities is an inkjet recording device employing a liquid ejection recording method. The inkjet recording device includes a recording head constructed of a liquid ejection head that ejects droplets of a recording liquid such as ink onto a recording medium to form an image on the recording medium.
The recording medium is often paper or the like fed from a sheet roll, constituted as one long continuous sheet wound around a core.
Also known is a detector that detects a trailing end of the recording medium roll. One example of the detector is retractably movable relative to a film roll, constituted as one long continuous film wound around a core. Film fed from the film roll is guided by a guide member, and as the film is fed out and an outer circumference of the film roll is reduced, the detector is moved forward to a position overlapping the film roll, without interfering with the rotation of the film roll, to detect the trailing end of the film roll.
With regard to types of sheet rolls, a 2-inch core and a 3-inch core are commonly used. In addition, in some sheet rolls, the trailing end is bonded to the core with glue or the like (hereinafter referred to as bonded sheet rolls), whereas in other sheet rolls, the sheet is merely wound around the core without the trailing end thereof being fixed to the core (hereinafter referred to as unbonded sheet rolls).
In a case in which both types of sheet rolls are usable, the trailing end of the unbonded sheet roll may contact or approach a detection member provided for detecting the trailing end of the bonded sheet roll. Consequently, the trailing end of the unbonded sheet roll may be erroneously detected as the trailing end of the bonded sheet roll even when the bonded sheet roll has not come to its end yet.
In particular, because a detection position where the trailing end of the bonded sheet roll with a relatively larger core is detected is close to a position where the trailing end of the unbonded sheet roll with a relatively smaller core is separated from the core, possibility of erroneous detection is increased.